Last year a purchased a couple of jugs of nitrogen fertilizer formulated for foliar feeding. These are used to assure that optimum levels of nitrogen are available to the buds at first growth before the roots are delivering much to growing buds and are often used by commercial growers to help give fruit spur leaves a head start. Such applications are usually made in early spring for apples but other species like cherries need a very late summer or early fall application to be effective (roots click in later). I’m thinking this application and timing might be helpful on wood one intends to use for grafting material next spring.
I already gave a dose to all trees in my nursery that I intend to transplant next season, believing that this might help compensate for the root damage of the transplant and help them establish more quickly. The problem is that I lack the discipline to actually do a controlled study. If any given procedure might help, I tend to treat every plant and not leave a bunch for a controlled study. I am even less likely to do a controlled study of the benefit of this kind of feeding of graft wood. It would require too much time devoted to organization of my graft wood and location of fertilized and unfertilized wood after grafting.
This is why I’m grateful for information derived from researchers who make their living entirely from doing this kind of work. It’s not something I enjoy doing, but love learning the results from. At the end of next season I will likely only have anecdotal observations to offer. I can compare grafting results to wood I’m given, but my own wood generally does better anyway.
Nowadays when someone sends me weak wood I don’t even bother trying to graft it. Grafting is too tedious to bother using wood that gives a reduced chance of success. Annual wood that has been slowed by leaf hopper or aphid damage or any other stress (including drought) is unlikely work as well as healthier, more vigorous wood, based on my unscientific anecdotal observation.